#!/usr/bin/perl
#
# Monitor external programs via SNMP (v. 1-3)
# (based on netsnmp-freespace.monitor)
#
# Usage: 
#       [-h]                # Usage
#       [-t Timeout]        # Timeout in ms (default: 1000000)
#       [-r Retries]        # Retries before failure (default: 5)
#       [-v SNMPversion]    # 1,2,2c or 3 (default: 1)
#       [-c Community]      # For SNMP v.1,2,2c (default: public)
#       [-u snmpuser]       # For SNMP v.3 (default: initial)
#       [-l seclevel]       # For SNMP v.3 (default: noAuthNoPriv)
#       [-A authpassphrase] # For SNMP v.3 
#       [-n num[,num...]]   # Zero-indexed external program number(s); programs
#                           # are numbered by the order they appear in the
#	                    # remote snmpd.conf. If monitoring specific programs
#	                    # on multiple hosts, they must be consistent!
#	                    # Default is to monitor all.
#       host [host ...]
#
# This script monitors one or more external programs run by the UCD
# SNMP agent. Specific programs to monitor can be specified with the
# "-n" option; these are zero-indexed in the order they appear in the
# monitored host's snmpd.conf file. Default is to monitor all.
#
# The summary output line will be of the form "host:name[,host:name]"
# where "name" is the name of the failing program (the "extNames"
# field as defined in snmpd.conf; not the path to the program). The
# detail lines will contain full error text from the failing program
# and the error value it returned.
#
# The script will exit with 0 value 1 for an extNames program failure
# and 2 for an SNMP error.
#
# BUGS AND LIMITATIONS: This is designed to handle programs that only
# return one line of output via snmpd; that is, with simple programs
# run via the "sh" or "exec" directives in the snmpd.conf file and NOT
# with programs run by "exec" and returning data in their own MIB
# tables. Actually, I've only gotten the "sh" directive to work with
# ucd-snmp-4.2.1 under Solaris. Also note that when given an external
# program number that doesn't exist on the monitored host, the script
# will return the output for program number 0 and will not report an
# error (see note below). In some situations (e.g. sending v. 1 request
# to a host configured only to respond to v. 3) the script will fail 
# silently, because the SNMP module doesn't report an error.
#
#
#    Copyright (C) 2001 Daniel J. Urist <durist@world.std.com>
#
#    This program is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; either version 2 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program; if not, write to the Free Software
#    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
use SNMP;
use Getopt::Std;

$ENV{'MIBS'} = "UCD-SNMP-MIB";

getopts("ht:r:v:c:u:l:A:n:");
my $VERSION = "0.2";
if($opt_h){
  print <<"USAGE";
$0 Version $VERSION by Daniel J. Urist <durist\@world.std.com>

Usage: 
       [-h]                # Usage
       [-t Timeout]        # Timeout in ms (default: 1000000)
       [-r Retries]        # Retries before failure (default: 5)
       [-v SNMPversion]    # 1,2,2c or 3 (default: 1)
       [-c Community]      # For SNMP v.1,2,2c (default: public)
       [-u snmpuser]       # For SNMP v.3 (default: initial)
       [-l seclevel]       # For SNMP v.3 (default: noAuthNoPriv)
       [-A authpassphrase] # For SNMP v.3 
       [-n num[,num...]]   # Zero-indexed external program number(s); programs
                           # are numbered by the order they appear in the
	                   # remote snmpd.conf. If monitoring specific programs
	                   # on multiple hosts, they must be consistent!
	                   # Default is to monitor all.
       host [host ...]

USAGE
  exit;
}

# FIXME we should probably offer all the v3 options that the SNMP module does
my $Timeout = $opt_t || 1000000;
my $Retries = $opt_r || 5;
my $SNMPVersion = $opt_v || 1;
my $Community = $opt_c || 'public';
my $SecName = $opt_u || 'initial'; 
my $SecLevel = $opt_l || 'noAuthNoPriv';
my $Authpass = $opt_A || '';

my %SNMPARGS = (
		Timeout => $Timeout,
		Version => $SNMPVersion,
	       );

if ($SNMPVersion eq "3"){
  $SNMPARGS{SecName} = $SecName;
  $SNMPARGS{SecLevel} = $SecLevel;
  $SNMPARGS{AuthPass} = $Authpass;
}
else{
  $SNMPARGS{Community} = $Community;
}

my @Extprognums = split(",", $opt_n);
my $RETVAL = 0;
my %Failures;
my %Longerr;
my $Session;

foreach $host (@ARGV) {
  $Session = new SNMP::Session(
			       DestHost => $host,
			       %SNMPARGS,
			      );
  unless( defined($Session) ) {
    $RETVAL = ($RETVAL == 1) ? 1 : 2;
    $Failures{"$host session error"} = "";
    $Longerr{"$host could not get SNMP session"} = "";
    next;
  }

  my $ext;
  my $v;
  my @q;
  # We are monitoring specific programs

  # FIXME If $ext is out of range, i.e. for example, if $ext is 2 and
  # there are only programs numbered 0 and 1, the returned value is
  # for program number 0. It seems to me we should get an SNMP error
  # back, but we don't; I suspect this is a bug in the SNMP module
  # since passing a bogus index to snmpwalk gives a "No Such Instance"
  # error. Unfortunately I also can't find a way to retrieve the index
  # number from the returned data, so I have nothing with which to
  # compare it and flag the error.

  if( defined(@Extprognums) ){
    foreach $ext (@Extprognums){
      $v = new SNMP::Varbind (["extIndex", $ext]);
      $Session->getnext($v);
      @q = $Session->get ([
			      ["extNames", $v->iid],	# 0
			      ["extCommand", $v->iid],  # 1
			      ["extResult", $v->iid],	# 2
			      ["extOutput", $v->iid],	# 3
			      ["extErrFix", $v->iid],	# 4
			     ]);

      if($q[2] != 0){
	$RETVAL = 1;
	$Failures{$host .":" . $q[0]} = "";
	$Longerr{$host .":" . $q[0] . " exited with code: " . $q[2] . ", error: \"" . $q[3] . "\""} = "";
      }
      if ($Session->{"ErrorStr"}) {
	$RETVAL = ($RETVAL == 1) ? 1 : 2;
	$Failures{$host} = "";
	$Longerr{"$host returned an SNMP error: " . $Session->{"ErrorStr"}} = "";
	last;
      }
    }
  }
  # We are monitoring all programs
  else{
    $v = new SNMP::Varbind (["extIndex"]);
    $Session->getnext($v);
    while (!$Session->{"ErrorStr"} && $v->tag eq "extIndex") {
      @q = $Session->get ([
			      ["extNames", $v->iid],	# 0
			      ["extCommand", $v->iid],  # 1
			      ["extResult", $v->iid],	# 2
			      ["extOutput", $v->iid],	# 3
			      ["extErrFix", $v->iid],	# 4
			     ]);
      if($q[2] != 0){
	$RETVAL = 1;
	$Failures{$host .":" . $q[0]} = "";
	$Longerr{$host .":" . $q[0] . " exited with code: " . $q[2] . ", error: \"" . $q[3] . "\""} = "";
      }
      if ($Session->{"ErrorStr"}) {
	$RETVAL = ($RETVAL == 1) ? 1 : 2;
	$Failures{$host} = "";
	$Longerr{"$host returned an SNMP error: " . $Session->{"ErrorStr"}} = "";
	last;
      }
      $Session->getnext($v);
    }
  }
}

if (scalar keys %Failures) {
    print join (", ", sort keys %Failures), "\n", "\n";
    print join ("\n", sort keys %Longerr), "\n";
}

exit $RETVAL;